Circulation for electrodeposit systems



f). DUNCAN.

CIRCULATION FOR ELECTRODEPOSI'F SYSTEMS;

APPLICATION FILED DEC. 11, 1920.

Pafnented Apr. 4, 19226 of the raceway or path.

UNITED STATES PATENT OFFICE.

CHARLES DUNCAN, OF PHILADELPHIA, PENNSYLVANIA.

CIRCULATION FOR ELECTRODEPOSIT SYSTEMS.

- Specification of Letters Patent.

Patented Apt-4,1922.

Application filed December 11, 1920. Serial No. 429,926.

tems, of which the followingis a'specifica-' tion.

Myinvention relates to baths for electrotyping and for similar processesin which a plurality of cathodes and anodes are used in the same bath.It is particularly suited to work where the cathodes and anodes areapproximately plane surfaces or planes as in electrotyping.

The main purpose of my invention is to secure circulation of thebathsolution so as to make possible the use of higher voltages withoutburning the deposit. and to-speed upth deposi't'rngoperation. For thispurpose I arrange the electrodes longitudinally of the bath in whatmight beacalled fluid series so that the fluid circulation of theelectrolyte providedbetween the plates of one set (i. e., one cathodeand zone anode) shall continue through successive sets of electrodes,preferably throughoutacourse, likened herein to a raceway or track, andforming a closed circuit. More specifically, by my 'invention Iarrange-the bath in theform of a track or path, preferably flattened onthe sides and ciirved at the ends, so that the liquids of the bath maycirculate throughou'mto the best advantage, and I provide mechanism forforcing the liquid of the bath lengthwise My invention relates both tothe methods disclosed and to the apparatus by which the methods may becarried out.

Further purpose will appear in the specification and in the claims.

Figure 1 is a top plan view of one form of my invention.

Figure 2 is a section of Figure 1, taken upon line 2--2 thereof.

Figure 3 is a fragmentary section corresponding in position to a portionof Figure 2, showing a modified form.

Figure 4 is a section upon line 4l-4 of the structure seen in Figure 3.

Figures 5- and 6 are fragmentary top plan views of modified forms. I

In the drawings similar numerals indicate like part. a

I have preferred to illustrate my invention by several structures of the.same general type but differing slightly in the means of providingcirculation and the placing of the electrodes only, among the variousforms in which my invention might be practiced, selecting this typebecause it is ractical, efliclent and inexpensive, and at t e same timewell illustrates the principles of my invention.

. In the electrotype shell the final printing surface is that surfaceof'the cathode farthest removed from the anode. This is made up oflines, points and relatively small surfaces which constitute the bottomsof grooves, holes and recesses in the face upon which'the coating isdeposited. Deposition of metal upon the high'spots ofthis face is easyand relatively rapid because they are exposed to good contact and thelines of flow to them ar of low resistance; but they do not I form theprinting surfaces.

On the other hand, the lines represented by thin rules -and thedepressionsfor type faces are quite deep and the lines of flow to themarehigh resistance lines. I

The deposit follows most readily the lines of low resistance flow, whereleast needed, and the solution available for the recesses isimpoverished by reason of this and because of the free movement ofsolution to the high spots as compared with the sluggish turn over ofsolution in the recesses.

Where the solution is impoverished by deposit of its metallic contentthere is immediate 'need for a supply of fresh ions for deposition. Thegeneral need of stirring the solution to assist in deposit has beenrecog nized and various efforts have been made to accomplish it, as byair. bubbles let loose in the bottom of the tank or bath and by forcedcirculation between the electrodes. However, where attempt was made tocause circulation between the electrode pairs, both the anodes andthecathodes have been placed with their planes extending across from oneside to the other of a generally rectangu-lar vat ortank and it has beennecessary to agitate the liquid separately at the'.inlet side. of eachpair without the 'directin assistance ofpartitioning off this part-of te tank to' form a raceway or fluid track. Not only, has,

most of the agitation caused been poorly applied, but, in the case ofbubbles, an excessive number of agitating bubbles has been required, andthe mechanical agitation has 7 set up irregular lines of flow withundesirable counter-currents. This 1s due 111 the case cited to thequick turn ot the circulating liquid required at the side of the bathbe.

cause the circulation is directly reversed in the short spaces betweenthe pairs or sets and the side of the tank.

I have attempted to secure smooth and easy circulation giving a maximumof fluid flow with a minimum of side flow or counter-currents and at aminimum of expense of tank space taken up and of energy required. Inaddition to this. the circulation mechanism is not in the way and iseasily ac,- cessible.

In the ilh stration the tank is shown at the feeders at 9 and 1t) andthe plates at 11, 12. It does not matter. for my invention which ofthese plates are anodes and which cathodes: nor is my invention confinedto a single cathode and a single anod in the width of the tank withinwhich they lie.

The fluid space for the bath within the tank is formed in an annularpath or track 13. flattened at the side portions 14 and 15 and curved atthe ends of 16 and 17 so as As is well known, the liquids used in thehath are heavier than water and there is a tendency of the acid solutionto settle, increasing in density toward the bottom.

Active swirling of the solution is necessary to a maximum density ofcurrent flow. By my invention I am able to maintain a current density ofat least 500 amperes to 600 amperes per square foot of cathode. This isconsidered a very high density at the present time.

Because of the tendency of the bath to greater density at the bottom.the propeller 18 shown in my preferred form is downwardly directed bymeans of its shaft 19 so as to stir up the liquid at the same time thatit gives circulation to the entire bath in the direction of the arrowsin Figure 1. As a result the liquid of the bath flows through thesuccessive sets (here pairs) of electrodes parallel to the faces of thecathodes and anodes in the'direction of the arrows, brush- 1 ing awayany bubbles that may have collected upon the surface. mixing the liquidand bringing all of the liquid successively in contact with thedifferent electrodes. v

The electrodes can be placed out of alignment, even when parallel inadjoining pairs, as shown in Figure 5. so as to break up settled linesof liquid flow within the bath. and multiple paths may be provided bythe use of three or more electrodes abreast (a single electrode at thecenter with surfaces oppositely facing to pair with differentelectrodes, if desired) as in Figure 6.

Screens at intervals are desir- The shaft 12 is shown as driven throughsprockets 13 and .11 and chain 15, from the shaft 16. and any suitablemotor or pulley intended to be typified by a motor 17.

In Figures 1 and 2 the mechanism is supported by means of brackets 18and 19 and may be permanently placed.

The shafts and blades may be made of copper. bronze. brass or othermetal which will be but little affected by the bath.

In Figure 3 and 4%. the driving mechanism is shown as comprisingpropeller 18 upon a shaft 19'. supported in a frame 27 and driventhrough a chain 21', sprockets 20, 22, shaft 23 and pulley 28. Thoughthe propeller blades are shown as much higher in the bath in thisfigure. it will be obvious that any depth of propeller and angle ofshaft may be provided for that is desired. and that the mechanism shownin these figures has the advantage of occupying very little spacelongitudinally of the bath and that it can be located quickly and easilyby means of a bracket 25 fastened at any point along the path of theliquid.

In Figure 5. the adjacent cathodes and anodes, arranged at intervalsalong the path of the liquid are placed differently for the purpose ofensuring more use of the liquid which in Figure limight flow outside andinside of the plates.

In Figure 6, I have shown two anodes as placed back-to-back with thecathodes on the outside, giving parallel paths between and increasingthe capacity for any given width of path.

Where desired the plates can be turned at an angle to the length of theliquid travel to ensure fresh liquid without setting up objectionablecross-currents or stopping the liquid travel.

The various changes shown are recognized by me as minor to the maininvention, are intended chiefly to indicate that my invention is notlimited to-the detail shown, and have advantage only in so far as theycooperate to secure better results in the use of my broad invention.

It will be evident that my invention may be applied either for thepurpose of permitting the use of high voltages with consequent .largeincrease in the permissible density of current flow and s eed ofdepositing the required metal; or in obtaining a firmer, denser and moreeffective deposit within the same time; and that these two advantagesmay both be secu'redto varying degrees within the judgment of thedesigner.

I recognize that the needs of installations and the preference of theindividual will produce many variations from what I have shown herein.but which will suggest themselves to the minds of those skilled in theart as a result of my disclosure, and I desue to cover all of thesechanges which come 1, 1 .1 eer within the reasonable spirit and scope ofmy invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

l. The method of facilitating the circulation of the liquid in a baththrough the spaces lying between the electrodes which consists inarranging successive pairs of electrodes with their faces substantiallyparallel in fluid series and giving the bath circulation between them ina diagonal downward direction.

2. The method of securing circulation of electro-depos ting materialbetween the cathodes and anodes within a bath which consists inarranging the cathode and anode pairs in tluid series longitudinally ofthe bath and in causing the liquid to flow between successive pairs andat the same time stirring up the bath by projecting the liquiddiagonally downwardly at one point for a number of pairs.

The method of securing circulation of electro-depositing materialbetween the plates of anode and cathode pairs within a bath. whichconsists in arranging'the bath in a relatively narrow annular circuit.in placing the'pairs in fluid series in successive positions along thelength of the circuit and in causing the fluid to flow about the circuitto secure circulation between the pairs and to avoid cross currents ofliquid.

l. The method of securing circulation of electro-depositing materialbetween the plates of a plurality of pairs of cathodes and anodes. whichconsists in arranging a closed track or path of How for the liquid,distributing the pairs at intervals along the length of the bath. anddriving the liquid throughout the bath by propelling means located welldown below the surface of the bath.

5. The method of rendering more effective circulation ofelectro-depositing material between the plates of a plurality of pairsof cathodes and anodes. which con sists in arranging a closed track orpath of flow for the liquid. distributing'the pairs at intervals alongthe length of the bath, and driving the liquid throughout the bath bypropelling means located Well down below the surface of the bath anddirected diagonally downwardly.

6. In an electro-deposit system, an annular bath in combination withelectrodes located at intervals along the length of the bath. and meansfor moving the bath about the annulus.

'7. In an electrotype system. an annular receptacle. an electro-depositbath therein, leads providing electric current for electrodeposit alongthe length of the bath. cathodes and anodes arranged in pairs to receivethe current, located at intervals along the length of the bath anddriving mechanism for moving the bath about the an-- nulus.

8. In an electrotype system. an annular receptacle. an electro-depositbath therein, leads providing electric current for electrodeposit alongthe length of the bath. cath' odes and anodes arranged in pairs toreceive the current. located at intervals along the length of the bathand driving mechanism for moving the bath about the annulus and "forstirring up the bottom of the bath.

9. In an electrotype system. an annular receptacle. a bath therein.cathode and anode pairs of plates arranged in series along the annulus.propeller agitating mechanism within the bath and directing thepropeller drive generally lengthwise of the bath and driving meansoutside the bath for the said propeller.

10. In an electrotype system. an annular receptacle. a bath therein.cathode and anode pairs of electrodes arranged in series along theannulus. a propeller. a shaft therefor extending into the bath anddirect ing the propeller drive generally lengthwise of the bath anddownwardly to stir up the bottom of the bath and driving means outsidethe bath for the said propeller shaft.

11. In an electrotype mechanism, an annular bath therein, a propellingmechanism effective to drive diagonally below the bath level. anddriving mechanism outside of the bath, adapted to be dipped into thebath at any point along the length'of the bath.

I CHARLES DUNCAN.

